In theory, the occurrence of two melting peaks could be attributed to the formation of different types of crystals, in a DSC curve. Is lack of interfacial adhesion an implication of this observation? Additionally, what are the exact implications of formation of imperfect crystals (different sizes and shapes) that is apparent from a broad melting peak of a DSC curve?
I believe the answers are highly dependent on the application. We extrude & draw filaments. When I see a double peak on the DSC it either means the material hasn't fully crystalized yet or there are impurities present. The implication of a wide peak here is that it is a more "production friendly" material.
Samantha Ryan Thank you very much for your answer. Would you mind elaborating on how a wide peak could mean a production friendly material? Is it because the material begins melting early on in the extruder? In the case of attributing a double peak to a material not being crystallized, are you referring to the cold crystallization peak which is usually exothermic?
Wide peak = a broader range of temperatures we can subject the material to during processing = a wider range of properties we can produce in the final filament.
I'm still relatively new to polymers and the word "crystallization" still seems mis-applied to me. I would prefer the term "aligned" for my understanding of the molecular happenings. On one end of the continuum the molecules are fully amorphous, random [and have the lower peak's melt point]. On the other end they are as aligned as is possible (crystallized) [and have the higher peak's melt point]. If the processing (solid stating) of the polymer (PET here) is complete, the lower peak will disappear because all of the molecules made it to the "aligned" state. I'm sure this is over simplified, but it is as much detail as I need for my job. =o)
- Badges
- Science topic
- Similar topics
- Physics
- Condensed Matter Physics
- Solid State Physics
- PEAKS